That personhood may come in degrees – rather than being “all or nothing” – is rather a dangerous thought, at least if applied to human persons4.

However, if we are inclined to extend the boundaries of personhood to include some higher non-human animals5 (or – in the future – artificial intelligences6) – but don’t want them to be on a par with human beings, for instance in moral accountability – we might have to allow the thought “person – 2nd class”, or something like that.

It seems clear that the qualities that qualify an individual to be a person (see the list7 in Dennett8, and also the main Note on Persons9), come in degrees.

The key point is probably whether personhood is an honorific rather than a substance10-term. If it is not a substance-term, as I believe it is not, then we have the option to provide – say – legal protection to the underlying substance – say human animal or human being11, and denying the epithet “person” to some human beings need not have the genocidal overtones that are usually suspected whenever such a thought is expressed.

So, maybe some persons are “more” persons than others and persons do indeed come in degrees. But maybe they are just better persons according to some criteria – whether ethical or metaphysical – and these criteria need to be sharply distinguished.

We can think of an analogy with animals. Some animals (eg. human beings – or, lest we be considered a special case - chimpanzees) are, according to many evaluative criteria, superior to other animals (worms). Yet all are animals. Now ethically and practically, some animals deserve greater consideration than others – it would appear that chimpanzees have a greater capacity for suffering than worms, for instance. So too, presumably, do exemplars of the same species, though not to the same degree except in severely pathological cases.

The question from the perspective of my research is not particularly the moral dimension – the dangerous thought that some persons may be more valuable than others – but whether there are degrees of personhood, or whether the best way of describing the situation of certain individuals being better qualified to be persons is to say that all are persons, but some are better persons than others.

This depends on what a person is. If the concept PERSON is itself a substance term (rather than being a property of substances), then we may be right to make the analogy with animals – where ANIMAL is a substance term. Otherwise, the analogy may not be apt.

The issue is highlighted by the possibility that some of the higher mammals are persons, nearly persons, or persons of reduced degree. If all persons are just persons, period, and all persons have to be treated equally (if that is our ethical outlook), then we might be stuck with duties that seem counter-intuitive (to some, at least).